The present invention relates to an electrostatic or variable-charge type ink-jet printer wherein a plurality of print head units are arranged in a horizontal array so that they may print an entire line at one time at high speed, leaving high quality printed images and wherein the deflection electrodes are so arranged that they may be shared in common by as many print head units as possible, whereby the multiple-nozzle print head may be remarkably simplified in construction.
With the conventional electrostatic type ink-jet printers, the charged ink drops are not deflected in the vertical direction. As a result, a gutter, which traps the uncharged or unused ink drops, must be disposed in the horizontal plane which includes the axis of the nozzle and the trajectories as well of the ink drops to be placed on a recording medium. Therefore it is impossible to place the ink drops at the positions in the shadow of the gutter. As a consequence, the conventional electrostatic ink drop steering systems are not adapted for use in the ink-jet in-line printers.
There have been therefore devised and demonstrated various types of multi-nozzle ink-jet printers wherein the charged ink drops are also deflected in the vertical direction in order to jump over the gutter so as to be placed at the positions in the shadow of the gutter, but they have a common defect that the vertical deflections of the charged ink drops vary from one print head unit to another and cannot be adjusted with a high degree of accuracy.